The present invention relates to a method useful in the technology of saccharification and fermentation of a waste cellulose resource.
Waste cellulose resources constitute a family of abundant non-depletive recyclable energy sources. Active efforts are being made to convert waste cellulose resources into either glucose or alcohol, and use this either as fuel or as a valuable starting material for chemical synthesis. Two methods are available for saccharifying waste cellulose resources: an enzyme saccharification process and an acid saccharification process. The first approach requires the recovery of spent acid and involves problems such as the formation of inhibitors that are deleterious to a subsequent fermentation step. Increasing attention, therefore, is being directed to the second approach which can be implemented under milder process conditions.
Waste cellulose resources such as chaff, straw, and waste wood are composites wherein cellulose, hemicellulose, and lignin are strongly bonded to one another, both physically and chemically. In order to realize efficient saccharification of the cellulose by an enzyme, the starting material must be broken down by some preliminary treatment so that good contact is established between the cellulose in the feed and the enzyme. Among preliminary treatments under study is one using a chemical such as acid or alkali to remove the lignin and other unwanted components and provide for the easy access of the anzyme to the starting material, and one that depends on mechanical grinding to provide larger surface areas. The first method uses large amounts of acids or alkalis as a sole chemical to remove lignin and other unwanted components and, therefore, is not only costly but also disadvantageous in terms of the recovery of the spent chemical. The second method is also uneconomical since it uses electric power to mechanically grind the starting material. Several reports have been written on the effects of ionizing radiation (hereunder simply referred to as radiation) on treatment of waste cellulose resources. Studies have also been made on the effects of the addition of delignifiers such as sulfuric acid, alcohols, and cadoxen, and a method has been proposed for illuminating cleaned waste cellulose resources with radiation after they have been swollen by such delignifiers. However, no report has been made of success in significantly accelerating the rate of irradiation of waste cellulose resources.